@@ -4,8 +4,8 @@
This file documents the CONFIG_PACKET_MMAP option available with the PACKET
socket interface on 2.4 and 2.6 kernels. This type of sockets is used for
-capture network traffic with utilities like tcpdump or any other that uses
-the libpcap library.
+capture network traffic with utilities like tcpdump or any other that needs
+raw acces to network interface.
You can find the latest version of this document at
@@ -14,6 +14,7 @@ You can find the latest version of this document at
Please send me your comments to
Ulisses Alonso Camaró <uaca@i.hate.spam.alumni.uv.es>
+ Johann Baudy <johann.baudy@gnu-log.net> (TX RING)
-------------------------------------------------------------------------------
+ Why use PACKET_MMAP
@@ -25,19 +26,24 @@ to capture each packet, it requires two if you want to get packet's
timestamp (like libpcap always does).
In the other hand PACKET_MMAP is very efficient. PACKET_MMAP provides a size
-configurable circular buffer mapped in user space. This way reading packets just
-needs to wait for them, most of the time there is no need to issue a single
-system call. By using a shared buffer between the kernel and the user
-also has the benefit of minimizing packet copies.
-
-It's fine to use PACKET_MMAP to improve the performance of the capture process,
-but it isn't everything. At least, if you are capturing at high speeds (this
-is relative to the cpu speed), you should check if the device driver of your
-network interface card supports some sort of interrupt load mitigation or
-(even better) if it supports NAPI, also make sure it is enabled.
+configurable circular buffer mapped in user space that can be used to either
+send or receive packets. This way reading packets just needs to wait for them,
+most of the time there is no need to issue a single system call. Concerning
+transmission, multiple packets can be sent through one system call to get the
+highest bandwidth.
+By using a shared buffer between the kernel and the user also has the benefit
+of minimizing packet copies.
+
+It's fine to use PACKET_MMAP to improve the performance of the capture and
+transmission process, but it isn't everything. At least, if you are capturing
+at high speeds (this is relative to the cpu speed), you should check if the
+device driver of your network interface card supports some sort of interrupt
+load mitigation or (even better) if it supports NAPI, also make sure it is
+enabled. For transmission, check the MTU (Maximum Transmission Unit) used and
+supported by devices of your network.
--------------------------------------------------------------------------------
-+ How to use CONFIG_PACKET_MMAP
++ How to use CONFIG_PACKET_MMAP to improve capture process
--------------------------------------------------------------------------------
From the user standpoint, you should use the higher level libpcap library, which
@@ -57,7 +63,7 @@ the low level details or want to improve libpcap by including PACKET_MMAP
support.
--------------------------------------------------------------------------------
-+ How to use CONFIG_PACKET_MMAP directly
++ How to use CONFIG_PACKET_MMAP directly to improve capture porcess
--------------------------------------------------------------------------------
From the system calls stand point, the use of PACKET_MMAP involves
@@ -66,6 +72,7 @@ the following process:
[setup] socket() -------> creation of the capture socket
setsockopt() ---> allocation of the circular buffer (ring)
+ option: PACKET_RX_RING
mmap() ---------> mapping of the allocated buffer to the
user process
@@ -97,13 +104,75 @@ also the mapping of the circular buffer in the user process and
the use of this buffer.
--------------------------------------------------------------------------------
++ How to use CONFIG_PACKET_MMAP directly to improve transmission process
+--------------------------------------------------------------------------------
+Transmission process is similar to capture as shown below.
+
+[setup] socket() -------> creation of the transmission socket
+ setsockopt() ---> allocation of the circular buffer (ring)
+ option: PACKET_TX_RING
+ bind() ---------> bind transmission socket with a network interface
+ mmap() ---------> mapping of the allocated buffer to the
+ user process
+
+[transmission] poll() ---------> wait for free packets (optional)
+ send() ---------> send all packets that are set as ready in
+ the ring
+ The flag MSG_DONTWAIT can be used to return
+ before end of transfer.
+
+[shutdown] close() --------> destruction of the transmission socket and
+ deallocation of all associated resources.
+
+Binding the socket to your network interface is mandatory (with zero copy) to
+know the header size of frames used in the circular buffer.
+
+As capture, each frame contains two parts:
+
+ --------------------
+| struct tpacket_hdr | Header. It contains the status of
+| | of this frame
+|--------------------|
+| data buffer |
+. . Data that will be sent over the network interface.
+. .
+ --------------------
+
+ bind() associates the socket to your network interface thanks to
+ sll_ifindex parameter of struct sockaddr_ll.
+
+ Initialization example:
+
+ struct sockaddr_ll my_addr;
+ struct ifreq s_ifr;
+ ...
+
+ strncpy (s_ifr.ifr_name, "eth0", sizeof(s_ifr.ifr_name));
+
+ /* get interface index of eth0 */
+ ioctl(this->socket, SIOCGIFINDEX, &s_ifr);
+
+ /* fill sockaddr_ll struct to prepare binding */
+ my_addr.sll_family = AF_PACKET;
+ my_addr.sll_protocol = ETH_P_ALL;
+ my_addr.sll_ifindex = s_ifr.ifr_ifindex;
+
+ /* bind socket to eth0 */
+ bind(this->socket, (struct sockaddr *)&my_addr, sizeof(struct sockaddr_ll));
+
+ A complete tutorial is available at: http://wiki.gnu-log.net/
+
+--------------------------------------------------------------------------------
+ PACKET_MMAP settings
--------------------------------------------------------------------------------
To setup PACKET_MMAP from user level code is done with a call like
+ - Capture process
setsockopt(fd, SOL_PACKET, PACKET_RX_RING, (void *) &req, sizeof(req))
+ - Transmission process
+ setsockopt(fd, SOL_PACKET, PACKET_TX_RING, (void *) &req, sizeof(req))
The most significant argument in the previous call is the req parameter,
this parameter must to have the following structure:
@@ -117,11 +186,11 @@ this parameter must to have the following structure:
};
This structure is defined in /usr/include/linux/if_packet.h and establishes a
-circular buffer (ring) of unswappable memory mapped in the capture process.
+circular buffer (ring) of unswappable memory.
Being mapped in the capture process allows reading the captured frames and
related meta-information like timestamps without requiring a system call.
-Captured frames are grouped in blocks. Each block is a physically contiguous
+Frames are grouped in blocks. Each block is a physically contiguous
region of memory and holds tp_block_size/tp_frame_size frames. The total number
of blocks is tp_block_nr. Note that tp_frame_nr is a redundant parameter because
@@ -336,6 +405,7 @@ struct tpacket_hdr). If this field is 0 means that the frame is ready
to be used for the kernel, If not, there is a frame the user can read
and the following flags apply:
++++ Capture process:
from include/linux/if_packet.h
#define TP_STATUS_COPY 2
@@ -391,6 +461,36 @@ packets are in the ring:
It doesn't incur in a race condition to first check the status value and
then poll for frames.
+
+Those defines are also used for transmission:
+
+ #define TP_STATUS_KERNEL 0 // Frame is available
+ #define TP_STATUS_USER 1 // Frame will be sent on next send()
+ #define TP_STATUS_COPY 2 // Frame is currently in transmission
+
+First, the kernel initializes all frames to TP_STATUS_KERNEL. To send a packet,
+the user fills a data buffer of an available frame, sets tp_len to current
+data buffer size and sets its status field to TP_STATUS_USER. This can be done
+on multiple frames. Once the user is ready to transmit, it calls send().
+Then all buffers with status equal to TP_STATUS_USER are forwarded to the
+network device. The kernel updates each status of sent frames with
+TP_STATUS_COPY until the end of transfer.
+At the end of each transfer, buffer status returns to TP_STATUS_KERNEL.
+
+ header->tp_len = in_i_size;
+ header->tp_status = TP_STATUS_USER;
+ retval = send(this->socket, NULL, 0, 0);
+
+The user can also use poll() to check if a buffer is available:
+(status == TP_STATUS_KERNEL)
+
+ struct pollfd pfd;
+ pfd.fd = fd;
+ pfd.revents = 0;
+ pfd.events = POLLOUT;
+ retval = poll(&pfd, 1, timeout);
+
--------------------------------------------------------------------------------
+ THANKS
--------------------------------------------------------------------------------
@@ -46,6 +46,7 @@ struct sockaddr_ll
#define PACKET_VERSION 10
#define PACKET_HDRLEN 11
#define PACKET_RESERVE 12
+#define PACKET_TX_RING 13
struct tpacket_stats
{
@@ -100,7 +101,7 @@ struct tpacket2_hdr
enum tpacket_versions
{
TPACKET_V1,
- TPACKET_V2,
+ TPACKET_V2
};
/*
@@ -156,7 +156,23 @@ struct packet_mreq_max
};
#ifdef CONFIG_PACKET_MMAP
-static int packet_set_ring(struct sock *sk, struct tpacket_req *req, int closing);
+static int packet_set_ring(struct sock *sk, struct tpacket_req *req,
+ int closing, int tx_ring);
+
+struct packet_ring_buffer {
+ char * *pg_vec;
+ unsigned int head;
+ unsigned int frames_per_block;
+ unsigned int frame_size;
+ unsigned int frame_max;
+
+ unsigned int pg_vec_order;
+ unsigned int pg_vec_pages;
+ unsigned int pg_vec_len;
+};
+
+struct packet_sock;
+static int tpacket_snd(struct packet_sock *po, struct msghdr *msg);
#endif
static void packet_flush_mclist(struct sock *sk);
@@ -166,12 +182,10 @@ struct packet_sock {
struct sock sk;
struct tpacket_stats stats;
#ifdef CONFIG_PACKET_MMAP
- char * *pg_vec;
- unsigned int head;
- unsigned int frames_per_block;
- unsigned int frame_size;
- unsigned int frame_max;
+ struct packet_ring_buffer rx_ring;
+ struct packet_ring_buffer tx_ring;
int copy_thresh;
+ atomic_t tx_pending_skb;
#endif
struct packet_type prot_hook;
spinlock_t bind_lock;
@@ -183,9 +197,6 @@ struct packet_sock {
struct packet_mclist *mclist;
#ifdef CONFIG_PACKET_MMAP
atomic_t mapped;
- unsigned int pg_vec_order;
- unsigned int pg_vec_pages;
- unsigned int pg_vec_len;
enum tpacket_versions tp_version;
unsigned int tp_hdrlen;
unsigned int tp_reserve;
@@ -204,8 +215,10 @@ struct packet_skb_cb {
#ifdef CONFIG_PACKET_MMAP
-static void *packet_lookup_frame(struct packet_sock *po, unsigned int position,
- int status)
+static void *packet_lookup_frame(struct packet_sock *po,
+ struct packet_ring_buffer *buff,
+ unsigned int position,
+ int status)
{
unsigned int pg_vec_pos, frame_offset;
union {
@@ -214,25 +227,50 @@ static void *packet_lookup_frame(struct packet_sock *po, unsigned int position,
void *raw;
} h;
- pg_vec_pos = position / po->frames_per_block;
- frame_offset = position % po->frames_per_block;
+ pg_vec_pos = position / buff->frames_per_block;
+ frame_offset = position % buff->frames_per_block;
- h.raw = po->pg_vec[pg_vec_pos] + (frame_offset * po->frame_size);
+ h.raw = buff->pg_vec[pg_vec_pos] + (frame_offset * buff->frame_size);
switch (po->tp_version) {
case TPACKET_V1:
- if (status != h.h1->tp_status ? TP_STATUS_USER :
- TP_STATUS_KERNEL)
+ if (status != h.h1->tp_status)
return NULL;
break;
case TPACKET_V2:
- if (status != h.h2->tp_status ? TP_STATUS_USER :
- TP_STATUS_KERNEL)
+ if (status != h.h2->tp_status)
return NULL;
break;
}
return h.raw;
}
+static inline void *packet_current_rx_frame(struct packet_sock *po, int status)
+{
+ return packet_lookup_frame(po, &po->rx_ring, po->rx_ring.head, status);
+}
+
+static inline void *packet_current_tx_frame(struct packet_sock *po, int status)
+{
+ return packet_lookup_frame(po, &po->tx_ring, po->tx_ring.head, status);
+}
+
+static inline void *packet_previous_rx_frame(struct packet_sock *po, int status)
+{
+ unsigned int previous = po->rx_ring.head ? po->rx_ring.head - 1 : po->rx_ring.frame_max;
+ return packet_lookup_frame(po, &po->rx_ring, previous, status);
+}
+
+static inline void *packet_previous_tx_frame(struct packet_sock *po, int status)
+{
+ unsigned int previous = po->tx_ring.head ? po->tx_ring.head - 1 : po->tx_ring.frame_max;
+ return packet_lookup_frame(po, &po->tx_ring, previous, status);
+}
+
+static inline void packet_increment_head(struct packet_ring_buffer *buff)
+{
+ buff->head = buff->head != buff->frame_max ? buff->head+1 : 0;
+}
+
static void __packet_set_status(struct packet_sock *po, void *frame, int status)
{
union {
@@ -646,7 +684,7 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, struct packe
macoff = netoff - maclen;
}
- if (macoff + snaplen > po->frame_size) {
+ if (macoff + snaplen > po->rx_ring.frame_size) {
if (po->copy_thresh &&
atomic_read(&sk->sk_rmem_alloc) + skb->truesize <
(unsigned)sk->sk_rcvbuf) {
@@ -659,16 +697,16 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, struct packe
if (copy_skb)
skb_set_owner_r(copy_skb, sk);
}
- snaplen = po->frame_size - macoff;
+ snaplen = po->rx_ring.frame_size - macoff;
if ((int)snaplen < 0)
snaplen = 0;
}
spin_lock(&sk->sk_receive_queue.lock);
- h.raw = packet_lookup_frame(po, po->head, TP_STATUS_KERNEL);
+ h.raw = packet_current_rx_frame(po, TP_STATUS_KERNEL);
if (!h.raw)
goto ring_is_full;
- po->head = po->head != po->frame_max ? po->head+1 : 0;
+ packet_increment_head(&po->rx_ring);
po->stats.tp_packets++;
if (copy_skb) {
status |= TP_STATUS_COPY;
@@ -759,10 +797,212 @@ ring_is_full:
goto drop_n_restore;
}
-#endif
+static void tpacket_destruct_skb(struct sk_buff *skb)
+{
+ struct packet_sock *po = pkt_sk(skb->sk);
+ void * ph;
+ BUG_ON(skb == NULL);
+ ph = packet_lookup_frame( po, &po->tx_ring, skb->mark, TP_STATUS_COPY);
-static int packet_sendmsg(struct kiocb *iocb, struct socket *sock,
+ BUG_ON(ph == NULL);
+ BUG_ON(atomic_read(&po->tx_pending_skb) == 0);
+
+ atomic_dec(&po->tx_pending_skb);
+ __packet_set_status(po, ph, TP_STATUS_KERNEL);
+
+ sock_wfree(skb);
+}
+
+static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff * skb, void * frame,
+ struct net_device *dev, int size_max, __be16 proto,
+ unsigned char * addr)
+{
+ union {
+ struct tpacket_hdr *h1;
+ struct tpacket2_hdr *h2;
+ void *raw;
+ } ph;
+ int to_write, offset, len, tp_len;
+ struct socket *sock = po->sk.sk_socket;
+ struct page *page;
+ void *data;
+ int err;
+
+
+ ph.raw = frame;
+
+ skb->protocol = proto;
+ skb->dev = dev;
+ skb->priority = po->sk.sk_priority;
+ skb->destructor = tpacket_destruct_skb;
+ skb->mark = po->tx_ring.head;
+
+ switch(po->tp_version) {
+ case TPACKET_V2:
+ tp_len = ph.h1->tp_len;
+ break;
+ default:
+ tp_len = ph.h1->tp_len;
+ break;
+ }
+
+ if (unlikely(tp_len > size_max)) {
+ printk(KERN_ERR "packet size is too long (%d > %d)\n",
+ tp_len, size_max);
+ return -EMSGSIZE;
+ }
+
+ skb_reserve(skb, LL_RESERVED_SPACE(dev));
+ data = ph.raw + po->tp_hdrlen;
+
+ if (sock->type == SOCK_DGRAM) {
+ err = dev_hard_header(skb, dev, ntohs(proto), addr,
+ NULL, tp_len);
+ if (unlikely(err < 0))
+ return -EINVAL;
+ } else if (dev->hard_header_len ) {
+ /* net device doesn't like empty head */
+ if(unlikely(tp_len <= dev->hard_header_len)) {
+ printk(KERN_ERR "packet size is too short "
+ "(%d < %d)\n", tp_len,
+ dev->hard_header_len);
+ return -EINVAL;
+ }
+
+ skb_push(skb, dev->hard_header_len);
+ err = skb_store_bits(skb, 0, data,
+ dev->hard_header_len);
+ if (unlikely(err))
+ return err;
+ }
+
+ err = -EFAULT;
+ to_write = tp_len - dev->hard_header_len;
+ data += dev->hard_header_len;
+ page = virt_to_page(data);
+ len = ((to_write > PAGE_SIZE) ? PAGE_SIZE : to_write);
+
+ offset = (int)((long)data & (~PAGE_MASK));
+ len -= offset;
+
+ skb->data_len = to_write;
+ skb->len += to_write;
+
+ while ( likely(to_write) ) {
+ get_page(page);
+ skb_fill_page_desc(skb,
+ skb_shinfo(skb)->nr_frags,
+ page++, offset, len);
+ to_write -= len;
+ len = (to_write > PAGE_SIZE) ? PAGE_SIZE : to_write;
+ offset = 0;
+ }
+
+
+ return tp_len;
+}
+
+static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
+{
+ struct socket *sock;
+ struct sk_buff *skb;
+ struct net_device *dev;
+ __be16 proto;
+ int ifindex, err, reserve = 0;
+ void * ph;
+ struct sockaddr_ll *saddr=(struct sockaddr_ll *)msg->msg_name;
+ int tp_len, size_max;
+ unsigned char *addr;
+ int len_sum = 0;
+
+ BUG_ON(po == NULL);
+ sock = po->sk.sk_socket;
+
+ if (saddr == NULL) {
+ ifindex = po->ifindex;
+ proto = po->num;
+ addr = NULL;
+ } else {
+ err = -EINVAL;
+ if (msg->msg_namelen < sizeof(struct sockaddr_ll))
+ goto out;
+ if (msg->msg_namelen < (saddr->sll_halen + offsetof(struct sockaddr_ll, sll_addr)))
+ goto out;
+ ifindex = saddr->sll_ifindex;
+ proto = saddr->sll_protocol;
+ addr = saddr->sll_addr;
+ }
+
+ dev = dev_get_by_index(sock_net(&po->sk), ifindex);
+ err = -ENXIO;
+ if (unlikely(dev == NULL))
+ goto out;
+
+ err = -EINVAL;
+ if (unlikely(sock->type != SOCK_RAW))
+ goto out_unlock;
+
+ reserve = dev->hard_header_len;
+
+ err = -ENETDOWN;
+ if (unlikely(!(dev->flags & IFF_UP)))
+ goto out_unlock;
+
+ size_max = po->tx_ring.frame_size - sizeof(struct skb_shared_info)
+ - po->tp_hdrlen - LL_ALLOCATED_SPACE(dev);
+
+ if (size_max > dev->mtu + reserve)
+ size_max = dev->mtu + reserve;
+
+
+ do
+ {
+ ph = packet_current_tx_frame(po, TP_STATUS_USER);
+ if(unlikely(ph == NULL))
+ continue;
+
+ skb = sock_alloc_send_skb(&po->sk, LL_ALLOCATED_SPACE(dev),
+ msg->msg_flags & MSG_DONTWAIT, &err);
+ if (unlikely(skb == NULL))
+ goto out_unlock;
+
+ __packet_set_status(po, ph, TP_STATUS_COPY);
+ atomic_inc(&po->tx_pending_skb);
+
+ tp_len = tpacket_fill_skb(po, skb, ph, dev, size_max, proto,
+ addr);
+ if(unlikely(tp_len < 0)) {
+ err = tp_len;
+ goto out_free;
+ }
+
+ err = dev_queue_xmit(skb);
+ if (unlikely(err > 0 && (err = net_xmit_errno(err)) != 0))
+ goto out_free;
+
+ packet_increment_head(&po->tx_ring);
+ len_sum += tp_len;
+ }
+ while(likely((ph != NULL)
+ || ((!(msg->msg_flags & MSG_DONTWAIT))
+ && atomic_read(&po->tx_pending_skb))));
+
+ err = len_sum;
+ goto out_unlock;
+
+out_free:
+ __packet_set_status(po, ph, TP_STATUS_USER);
+ atomic_dec(&po->tx_pending_skb);
+ kfree_skb(skb);
+out_unlock:
+ dev_put(dev);
+out:
+ return err;
+}
+#endif
+
+static int packet_snd(struct socket *sock,
struct msghdr *msg, size_t len)
{
struct sock *sk = sock->sk;
@@ -853,6 +1093,19 @@ out:
return err;
}
+static int packet_sendmsg(struct kiocb *iocb, struct socket *sock,
+ struct msghdr *msg, size_t len)
+{
+#ifdef CONFIG_PACKET_MMAP
+ struct sock *sk = sock->sk;
+ struct packet_sock *po = pkt_sk(sk);
+ if (po->tx_ring.pg_vec)
+ return tpacket_snd(po, msg);
+ else
+#endif
+ return packet_snd(sock, msg, len);
+}
+
/*
* Close a PACKET socket. This is fairly simple. We immediately go
* to 'closed' state and remove our protocol entry in the device list.
@@ -891,10 +1144,13 @@ static int packet_release(struct socket *sock)
packet_flush_mclist(sk);
#ifdef CONFIG_PACKET_MMAP
- if (po->pg_vec) {
+ {
struct tpacket_req req;
memset(&req, 0, sizeof(req));
- packet_set_ring(sk, &req, 1);
+ if (po->rx_ring.pg_vec)
+ packet_set_ring(sk, &req, 1, 0);
+ if (po->tx_ring.pg_vec)
+ packet_set_ring(sk, &req, 1, 1);
}
#endif
@@ -1411,6 +1667,7 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv
#ifdef CONFIG_PACKET_MMAP
case PACKET_RX_RING:
+ case PACKET_TX_RING:
{
struct tpacket_req req;
@@ -1418,7 +1675,7 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv
return -EINVAL;
if (copy_from_user(&req,optval,sizeof(req)))
return -EFAULT;
- return packet_set_ring(sk, &req, 0);
+ return packet_set_ring(sk, &req, 0, optname == PACKET_TX_RING);
}
case PACKET_COPY_THRESH:
{
@@ -1438,7 +1695,7 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv
if (optlen != sizeof(val))
return -EINVAL;
- if (po->pg_vec)
+ if (po->rx_ring.pg_vec || po->tx_ring.pg_vec)
return -EBUSY;
if (copy_from_user(&val, optval, sizeof(val)))
return -EFAULT;
@@ -1457,7 +1714,7 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv
if (optlen != sizeof(val))
return -EINVAL;
- if (po->pg_vec)
+ if (po->rx_ring.pg_vec || po->tx_ring.pg_vec)
return -EBUSY;
if (copy_from_user(&val, optval, sizeof(val)))
return -EFAULT;
@@ -1701,13 +1958,17 @@ static unsigned int packet_poll(struct file * file, struct socket *sock,
unsigned int mask = datagram_poll(file, sock, wait);
spin_lock_bh(&sk->sk_receive_queue.lock);
- if (po->pg_vec) {
- unsigned last = po->head ? po->head-1 : po->frame_max;
-
- if (packet_lookup_frame(po, last, TP_STATUS_USER))
+ if (po->rx_ring.pg_vec) {
+ if (packet_previous_rx_frame(po, TP_STATUS_USER))
mask |= POLLIN | POLLRDNORM;
}
spin_unlock_bh(&sk->sk_receive_queue.lock);
+ spin_lock_bh(&sk->sk_write_queue.lock);
+ if (po->tx_ring.pg_vec) {
+ if (packet_current_tx_frame(po, TP_STATUS_KERNEL))
+ mask |= POLLOUT | POLLWRNORM;
+ }
+ spin_unlock_bh(&sk->sk_write_queue.lock);
return mask;
}
@@ -1783,20 +2044,24 @@ out_free_pgvec:
goto out;
}
-static int packet_set_ring(struct sock *sk, struct tpacket_req *req, int closing)
+static int packet_set_ring(struct sock *sk, struct tpacket_req *req, int closing, int tx_ring)
{
char **pg_vec = NULL;
struct packet_sock *po = pkt_sk(sk);
int was_running, order = 0;
+ struct packet_ring_buffer *rb;
+ struct sk_buff_head *rb_queue;
__be16 num;
int err = 0;
+ rb = tx_ring ? &po->tx_ring : &po->rx_ring;
+ rb_queue = tx_ring ? &sk->sk_write_queue : &sk->sk_receive_queue;
+
if (req->tp_block_nr) {
int i;
/* Sanity tests and some calculations */
-
- if (unlikely(po->pg_vec))
+ if (unlikely(rb->pg_vec))
return -EBUSY;
switch (po->tp_version) {
@@ -1813,16 +2078,16 @@ static int packet_set_ring(struct sock *sk, struct tpacket_req *req, int closing
if (unlikely(req->tp_block_size & (PAGE_SIZE - 1)))
return -EINVAL;
if (unlikely(req->tp_frame_size < po->tp_hdrlen +
- po->tp_reserve))
+ po->tp_reserve))
return -EINVAL;
if (unlikely(req->tp_frame_size & (TPACKET_ALIGNMENT - 1)))
return -EINVAL;
- po->frames_per_block = req->tp_block_size/req->tp_frame_size;
- if (unlikely(po->frames_per_block <= 0))
+ rb->frames_per_block = req->tp_block_size/req->tp_frame_size;
+ if (unlikely(rb->frames_per_block <= 0))
return -EINVAL;
- if (unlikely((po->frames_per_block * req->tp_block_nr) !=
- req->tp_frame_nr))
+ if (unlikely((rb->frames_per_block * req->tp_block_nr) !=
+ req->tp_frame_nr))
return -EINVAL;
err = -ENOMEM;
@@ -1835,17 +2100,19 @@ static int packet_set_ring(struct sock *sk, struct tpacket_req *req, int closing
void *ptr = pg_vec[i];
int k;
- for (k = 0; k < po->frames_per_block; k++) {
+ for (k = 0; k < rb->frames_per_block; k++) {
__packet_set_status(po, ptr, TP_STATUS_KERNEL);
ptr += req->tp_frame_size;
}
}
- /* Done */
- } else {
+ }
+ /* Done */
+ else {
if (unlikely(req->tp_frame_nr))
return -EINVAL;
}
+
lock_sock(sk);
/* Detach socket from network */
@@ -1866,20 +2133,19 @@ static int packet_set_ring(struct sock *sk, struct tpacket_req *req, int closing
if (closing || atomic_read(&po->mapped) == 0) {
err = 0;
#define XC(a, b) ({ __typeof__ ((a)) __t; __t = (a); (a) = (b); __t; })
-
- spin_lock_bh(&sk->sk_receive_queue.lock);
- pg_vec = XC(po->pg_vec, pg_vec);
- po->frame_max = (req->tp_frame_nr - 1);
- po->head = 0;
- po->frame_size = req->tp_frame_size;
- spin_unlock_bh(&sk->sk_receive_queue.lock);
-
- order = XC(po->pg_vec_order, order);
- req->tp_block_nr = XC(po->pg_vec_len, req->tp_block_nr);
-
- po->pg_vec_pages = req->tp_block_size/PAGE_SIZE;
- po->prot_hook.func = po->pg_vec ? tpacket_rcv : packet_rcv;
- skb_queue_purge(&sk->sk_receive_queue);
+ spin_lock_bh(&rb_queue->lock);
+ pg_vec = XC(rb->pg_vec, pg_vec);
+ rb->frame_max = (req->tp_frame_nr - 1);
+ rb->head = 0;
+ rb->frame_size = req->tp_frame_size;
+ spin_unlock_bh(&rb_queue->lock);
+
+ order = XC(rb->pg_vec_order, order);
+ req->tp_block_nr = XC(rb->pg_vec_len, req->tp_block_nr);
+
+ rb->pg_vec_pages = req->tp_block_size/PAGE_SIZE;
+ po->prot_hook.func = (po->rx_ring.pg_vec) ? tpacket_rcv : packet_rcv;
+ skb_queue_purge(rb_queue);
#undef XC
if (atomic_read(&po->mapped))
printk(KERN_DEBUG "packet_mmap: vma is busy: %d\n", atomic_read(&po->mapped));
@@ -1906,7 +2172,8 @@ static int packet_mmap(struct file *file, struct socket *sock, struct vm_area_st
{
struct sock *sk = sock->sk;
struct packet_sock *po = pkt_sk(sk);
- unsigned long size;
+ unsigned long size, expected_size;
+ struct packet_ring_buffer *rb;
unsigned long start;
int err = -EINVAL;
int i;
@@ -1917,23 +2184,38 @@ static int packet_mmap(struct file *file, struct socket *sock, struct vm_area_st
size = vma->vm_end - vma->vm_start;
lock_sock(sk);
- if (po->pg_vec == NULL)
+
+ expected_size = 0;
+ if (po->rx_ring.pg_vec)
+ expected_size += po->rx_ring.pg_vec_len * po->rx_ring.pg_vec_pages * PAGE_SIZE;
+ if (po->tx_ring.pg_vec)
+ expected_size += po->tx_ring.pg_vec_len * po->tx_ring.pg_vec_pages * PAGE_SIZE;
+
+ if (expected_size == 0)
goto out;
- if (size != po->pg_vec_len*po->pg_vec_pages*PAGE_SIZE)
+
+ if (size != expected_size)
goto out;
start = vma->vm_start;
- for (i = 0; i < po->pg_vec_len; i++) {
- struct page *page = virt_to_page(po->pg_vec[i]);
- int pg_num;
-
- for (pg_num = 0; pg_num < po->pg_vec_pages; pg_num++, page++) {
- err = vm_insert_page(vma, start, page);
- if (unlikely(err))
- goto out;
- start += PAGE_SIZE;
+
+ for(rb = &po->rx_ring; rb <= &po->tx_ring; rb++) {
+ if (rb->pg_vec == NULL)
+ continue;
+
+ for (i = 0; i < rb->pg_vec_len; i++) {
+ struct page *page = virt_to_page(rb->pg_vec[i]);
+ int pg_num;
+
+ for (pg_num = 0; pg_num < rb->pg_vec_pages; pg_num++, page++) {
+ err = vm_insert_page(vma, start, page);
+ if (unlikely(err))
+ goto out;
+ start += PAGE_SIZE;
+ }
}
}
+
atomic_inc(&po->mapped);
vma->vm_ops = &packet_mmap_ops;
err = 0;
New packet socket feature that makes packet socket more efficient for transmission. - It reduces number of system call through a PACKET_TX_RING mechanism, based on PACKET_RX_RING (Circular buffer allocated in kernel space which is mmapped from user space). - It minimizes CPU copy using fragmented SKB. Signed-off-by: Johann Baudy <johann.baudy@gnu-log.net> -- Hi All, Before going on submitting process, I would like to get your opinion on those below points: 1#: In order to make such feature, each packet header of the circular buffer can be set to one of those three statuses: - TP_STATUS_USER: packet buffer needs to be transmitted. On this status, Kernel: - Allocates a new skb - Attaches packet buffer pages - Changes skb destructor - Stores packet header pointer or index into skb - Changes the packet header status to TP_STATUS_COPY; - Sends it to device. - TP_STATUS_COPY: packet transmission is ongoing On this status, the skb destructor (called during skb release) - Gets packet header pointer linked to skb pointer; - Changes the packet header status to TP_STATUS_KERNEL; - TP_STATUS_KERNEL: packet buffer has been transmitted and buffer is ready for user. As you can see, this skb destructor needs packet header pointer related to sk_buff pointer to change header status. I've first used skb->cb (control buffer) to forward this parameter to destructor. Unfortunately, this one seems to be overwritten in packet queue mechanism. So I've finally chosen skb->mark to store buffer index. Can I use skb->mark in such condition? If not, what is the best solution: - new field in sk_buff struct? - a sk_buff pointer array [NB_FRAME] (one index matches to one skb pointer)? (parsing is not really good for cpu load) - other ? 2#: Do I need to protect send() procedure with some locks? Especially when changing status from TP_STATUS_USER to TP_STATUS_COPY to prevent kernel from sending a packet buffer twice? (If two send() are called from different threads In SMP for example) Or is it implicit? Thanks in advance, Johann Baudy -- Documentation/networking/packet_mmap.txt | 132 ++++++++-- include/linux/if_packet.h | 3 +- net/packet/af_packet.c | 422 +++++++++++++++++++++++++----- 3 files changed, 470 insertions(+), 87 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html